Grinding apparatus



Sept. 21, 1954 o. ENGLER I 2,689,689

GRINDING APPARATUS Filed Oct. 9, 1951 2 Sheets-Sheet 1 INVENTOR. O-rTo E/YGLER p 21, 1954 o. ENGLER 2,689,689

\ GRINDING APPARATUS Filed 061;. 9, 1951 2 Sheets-Sheet 2 Patented Sept. 21, 1954 GRINDING APPARATUS Otto Engler, Dusseldorf, Germany, assignor to Max Berz, Kochel, Germany Application October 9, 1951, Serial No. 250,495

Claims priority, application Germany October 9, 1950 20 Claims. 1

The present invention relates to a grinding apparatus of the type in which grinding surfaces move with respect to each other to pulverize a material.

Conventional grinding machines of the above type have a grinding disc which engages a plurality ofgrinding rollers, the latter usually being hingedly mounted by means of pendulum-like supports, so that the rollers may give way with respect to the grinding disc when a particularly hard material is ground. The purpose of this.

yieldable mounting of the rollers is to prevent breaking of the machine parts.

This latter type of conventional construction has many defects because the pivotal mountings of the rollers must be Well greased in order to be properly lubricated, and these pivotal mountings are generally inaccessibly located sothat it is difficult to maintain the parts of the machine properly lubricated. Moreover it very frequently happens that dust arising from the material being ground enters into the bearings and causes the same to become worn after a very short time.

One of the objects of the present invention is to overcome all of the above defects.

Another object of the present invention is to provide a grinding machine with grinding parts which will need no lubrication.

An additional object of the present invention is to provide an extremely simple mounting and guiding means for the grinding rollers of a grinding machine.

A still further object'of the present invention is to provide a grinding machine with a means for preventing dust from getting into bearings of the machine. r

Yet another object of the present invention is to provide a grinding machine made of few, relatively simple, easily constructed parts, which are easy to maintain and freely accessible.

With the above objects in view, the present invention mainly consists of a grinding machine in which a grinding disc is mounted for rotation about an axis. This disc has on one side thereof an annular grinding face which is engaged by the peripheral grinding face of at least one grinding roller which has opposite side faces from which a pair of shaft portions extend. A spring means is operatively connected to the roller, through the medium of a stationary pressure ring, to urge the roller toward the disc in a direction substantially parallel to the axis of rotation of the latter. The contacting surfaces of the roller and pressure ring are made of hard 2 metal. roller are respectively located in slots respectively formed in a pair of ring members and extending in a direction substantially parallel to the axis of rotation of the disc, so that the roller is free to move in the direction of the slots. These ring members are rotatably mounted within the housing of the grinding machine. If desired, the shaft members of the grinding roller may be respectively located in bores of members connected to these ring members, and in this latter case the ring members are movable with the roller in a direction substantially parallel to the axis of rotation of the grinding disc. With this construction, a roller mounting which requires lubrication is entirely eliminated, and the hard metal at the contacting surfaces of the moving parts guarantees that these parts will give service for a long time before they will become. appreciably worn.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. 1 is a schematic, vertical, sectional view through one possible grinding machine constructed in accordance with the present invention;-

Fig. 2 is a schematic, vertical, sectional fragmentary view of a somewhat different embodiment of a grinding machine constructed in accordance with the present invention} and Fig. 3 is a partly sectional plan view of a construction similar to that of Fig. 2, showing a slightly different embodiment from that illustrated in Fig. 2.

Referring now to the drawings, there is shown in Fig. 1 a grinding machine having a cylindrical housing portion 1 which is flanged at its upper edge where it is connected to the flanged lower edge of a conical cover 3 of the grinding machine. The cylindrical housing portion I is supported at its lower flanged edge on the frame portion 2 of the grinding machine. In this frame portion 2 there is located a driving member 6 which is rotated by a driving mechanism not shown. From the member 6 there extends a stud 5 fixedly connected to the member 6 for rotation therewith and engaging a recess in the bottom of the grinding disc 4 so as to cause the The shaft portions extending from the to the rollers i5.

latter to rotate with the member 6. For example, the stud and the mating recess of disc 4 may be of a non-circular cross-section so that they are constrained to rotate together. Supported on the frame portion 2 is a ring member 8, of a U-shaped' cross-section, which has an annular projection on its upper surface located in an annular groove formed in a lower annular surface portion of the disc 4, so that the interior of the housing I, in which the disc 4 ismounted for rotation about a vertical axis, is sealed off from the frame portion 2 by this ring member 8. A ring member 9 is fixedly mounted within the housing portion I, by means of the barmembers Ii], and is located closely about the disc 4 so as to form an annular bearing for the latter.

The disc 4 is provided on its upper surface with an annular shoulder portion II upon which a grinding ring I2 having a grinding surface I4 is located. The ring I2 is prevented from rotation with respect to the disc 4 by the leaf spring members I3 located in opposite grooves formed in the engaging surfaces of annular portion II and ring member I2. If desired, the annular grinding portion may be formed integrally with the disc 4, as shown in Fig. 2.

A plurality of grinding rollers l5 having their axes inclined to the axisof rotation of disc 4 are located within the housing I and have their peripheral grinding face portion I6 engaging the annular grinding face I4, as illustrated. These grinding rollers l5 have opposite side faces from which shaft portions [1 and I8 respectively extend, theseshaft portions being fixedly connected The shaft portions I1 and I8 are respectively'located in slots I9 :and 20 which extend in a direction parallel to the axis of rotation of disc 4 and are respectively formed in a pair of annular ring members 2I and 22 which are located concentrically with respect to each other about the axis of rotation of disc 4.

As is illustrated in Fig. 1, these ring members 21 and 22 may conveniently take the form of annular I-beams and are fixedly connected to each other by bar members 23, which may also be I- beams and which are inclined due to the fact that the ring member 22 is located nearer :to the disc 4 than the ring member 2I. Fixedly mounted on the upper surface of ring member 2I is an annular angle bar 24 which is mounted for rotation on a plurality of roller members 3|, which are themselves mounted for rotation on the inner surface of the housing portion I, as is shown in Fig. l. The lowersurfaces of the ring member 2| engages a plurality of rollers 3 I similar to rollers 3.! ;and also mounted on the interior of housing portion l'.

The rollers I5 are formed'with a profiled, annular, hard metal surface which engages the lower, profiled, mating, hard metal surface of the pressure ring 26, which is stationary during the operation of the grinding machine. A plurality of bar members 2! are fixedly mounted on the interior surface of the housing portion I and extend toward the pressure ring 26, these members 2? each having an inner end'portion located between a pair of members fixedly mounted on the annular outer side face of ring member 26 and located closely adjacent to the inner .end portion of member 27 so that the pressure ring 26 is mounted only for vertical movement in the housing portion I in a direction substantially parallel to the axis of rotation of disc 4. The lower surface of ring 26 forms a track for rollers I5.

A ring member 25 is slidably mounted Within the housing portion I for movement in a direction substantially parallel to the axis of rotation of disc 4 and may be adjustably located at a desired position with respect to pressure ring 26 by any suitable means such as, for example, the set screw members 25 .threadedly mounted in threaded openings formed in the housing portion :I and engaging the outer periphery of the ring 25.

Located between the pressure ring 25 and adjustable ring 25 are the springs 28 which urge the pressure ring 26 and the rollers I5 toward the grinding disc 4 with a pressure which may be regulated by adjustment of ring 25.

A conduit 29 leads through the wall of housing portion 3 to the interior thereof. On the inside of housing portion 3 the conduit 9 leads onto a chute 30 which is pivotally supported from the hinge pin 39 located in the housing portion 3. This chute 30 rests on an inner, annular, inclined surface portion of ring 25 so that material to be ground may be supplied to the grinding surface through elements 29 and 39.

A conduit 40 leads through the frame portion 2 to the interior of housing portion I by a .path located about the .ring member 9. 46 serves to supply air to the interior of housing portion I.

A grinding machine of the above type may be used, for example, to pulverize coal so as to provide a combustible powder for the burners of a furnace, for example, and in this latter event the cover portion 3 will be connected by any suitable conduit means (not shown) to such burners, a sieve, for example, being located in such .a conduit means to prevent relatively large pieces of fuel from being carried to the burners, these relatively large pieces of fuel falling back to the grinding machine to be further pulverized thereby.

The above described grinding machine operates as follows:

The drive means rotates member 6 which causes the disc 4 to rotate therewith, this disc 4 1 rotating the rollers I5 by contact therewith both about their ownaxes and about the axis of rotation of disc 4, the rollers I5 rolling with respect to the pressure ring 26. Material to be ground is fed to the rollers and grinding disc through elements 29 and 30, and air supplied through conduit 40 rises upwardly through the housing portion I to carry dust produced by the pulverizing action of the grinding machine to a burner, as described above. If extremely hard pieces of material are fed to the grinding machine, the rollers I 5, due to the mounting of the shaft portions I1 and It in the slots i9 and .20, respectively, are free to move in a direction substantially parallel to the axis of rotation of disc 4, and the pressure ring 26 is free to move therewith in substantially the same direction. The ring members 2| and 22 rotate on the rollers 3| and 3! about the axis of rotation of disc 4 with the rollers I5.

The embodiment of the invention which is illustrated in Fig. 2 has substantially the same parts as the embodiment illustrated in Fig. l and accomplishes the same results. The essential difference between the embodiments of Figs. 1

and 2 is that the embodiment of Fig. 2 does not This conduit upwardly into the housing portion I, this extension 34 carrying on its upper end a spherically shaped member 33. Located about the extension 34 of shaft 35 is a cap means 32 which includes an upper closure member 36 formed with a concave inner face which engages the spherical member 33. The inner ring member 22 is fixedly connected to the bottom edge of the cap means 32 so as to be supported thereby, and ring member 22 is rigidly connected to the outer ring member 21 by the bar members 23 which have flanged opposite ends respectively connected to the ring members 2| and 22. A bearing member 4| is mounted within the ring member 22 to engage the extension 34 of shaft 35 so as to prevent tilt-- ing of the cap means 32 about the extension 34 of shaft member 35.

On the outer surface of ring member 22 there are fixedly mounted a pair of plate members which extend in a direction parallel to shaft 35 and are located on opposite sides of shaft portion l8 extending from roller I5. On the inner surface of ring 2| there are also a fixedly mounted pair of plate members extending in a direction parallel to shaft 35 and located on opposite sides of shaft 11. Extending between and being fix edly connected to each of these pairs of plate members is a cross-plate member H which is formed with a bore through which one of the shaft portions l1, [8' extends these shaft portions having fixedly mounted thereon the collar members 31 and 38, respectively, which engage the cross-plate members to limit movement of the rollers in the direction of the shaft portions extending from the opposite sides thereof, respectively. The shaft 35 and its extension 34 is formed with a bore 42 which opens at 43 into the interior of the cap means 32.

The above-described construction operates in substantially the same manner as the embodiment of Fig. 1 except that the ring members 21 and 22 are movable along with the rollers l and pressure ring 26 in a direction parallel to the axis of rotation of disc 4, these ring members being mounted about extension 34 of shaft 35 for rotation with respect thereto. Air pressure is supplied to the interior of cap means 32 by way of the bore 42, 43 so as to prevent dust from entering the interior of the cap means 32, and the bearings within cap means 32 are thereby kept free of any dust.

Fig. 3 is a plan view of a grinding apparatus substantially the same as that of Fig. 2, the only difference being that the above-described crossplate members H are omitted and each shaftportion extending from the rollers I5 is simply guided between a pair of plate members fixedly mounted on one of the ring members and located on opposite sides of the shaft portion, as described above. In the embodiment of Fig. 1 there are three rollers spaced at 120 from each other as illustrated in Fig. 3.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of grinding apparatus differing from the types described above.

While the invention has been illustrated and described as embodied in grinding apparatus having a grinding roller mounting which requires no lubrication, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention'that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; spring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising a pair of ring members located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions.

2. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; pring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising a pair of ring members located concentrically about said axis, being mounted in said housing for movement in a direction substantially parallel to said axis and each having a pair of platemembers fixedlymounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions, and a crossplate member fixedly mounted on and extending between said pair of plate members and being formed with a bore through which one of said shaft portions extends.

3. A grinding machine, comprising in combination, a housing having a side wall provided with an inner cylindrical surface located about a central axis of said housing; bearing means mounted on said inner surface; a grinding disc mounted in said housing for rotation about said axis, saidgrinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; spring means operatively connected to said roller for urging'th'e same against said disc in'a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions'to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising outer and inner ring members fixedly connected to each other, located concentrically about said axis and each being formed with a slot extending in a direction substantially parallel to said axis and being located about one of said shaft portions, said outer ring member being mounted on said bearing means for rotation about said axis.

4. A grinding machine, comprising in combination, a housing; a grinding disc mounted on a central shaft member in said housing for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and haVing opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; spring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising outer and inner ring members fixedly connected to each other, located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions, said inner ring member being supported on said central shaft member for retaticn with respect thereto.

5. A grinding machine, comprising in combination, a housing; a grinding disc mounted on a central shaft member in said housing for rotation about an axis, said grinding disc having anannular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; spring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising outer and inner ring members fixedly connected to each other, located concentrically about said axis, being mounted in said housing for movement in a direction substantially parallel to said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions, and a crossplate member fixedly mounted on and extending between said pair of plate members and being formed with a bore through which one of said shaft portions extends, said inner ring member being supported on said central shaft member for rotation with respect thereto.

6. A grinding machine, comprising in combination, a housing; a grinding disc mounted in 1 said housing, on a central shaft member having an outer end, for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least "one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces; a pair of shaft portions respectively extending from said oppoisite side faces of said roller; spring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising outer and inner members fixedly connected to each other, located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions; and cap means mounted on said outer end of and being located about said central shaft member for rotation with respect thereto and being fixedly connected to said inner ring member to support the latter for rotation therewith.

'7. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing, on a central shaft member having an outer end, for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; spring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; guiding means operatively connected to said shaft portions to guide said roller for free movement in'a direction substantially parallel to said axis,,said' grinding means comprising outer and inner'ring members fixedly connected to each other, located concentrically about'said axis and each having a pair of-plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions; cap means mounted on said outer end of and being located about said central shaft member, for rotation with respect thereto and being fixedly connected to said inner ring member to support the latter for rotation therewith; and fluid pressure means communicating with the interior of said capmeans to prevent foreign matter from entering the same.

8. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing, on a central shaft member having an outer end, for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of' said disc and having opposite side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; spring means operatively connected to said roller for urging the same against said disc in a direction substantially parallel to said axis; guiding means operatively connected to said shaft portions to guide said roller for free movement in a direction substantially parallel to said axis, said guiding means comprising outer and inner ring members fixedly connected to each other, located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions; cap means mounted on said outer end of and being located about said central shaft member for rotation with respect thereto and being fixedly connected to said inner ring member to suppoit the latter for rotation therewith; and bearing means located between said cap means and central shaft member to prevent tilting of said cap means with respect to said shaft member.

9. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces and an annular surface portion located adjacent said peripheral grinding face and one of said side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; a pressure ring located about said axis and having a surface portion engaging said annular surface portion of said roller, said pressure ring being mounted in said housing only for movement in a direction substantially parallel to said axis; spring means op- V eratively connected to said pressure ring for urging the same against said roller in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement with said pressure ring in a direction substantially parallel to said axis.

10. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces and an annular surface portion of hard metal located adjacent one of said side faces; a pair of shaft portions respectively extending from said opposite side faces ofsaid roller; a pressure ring located about said axis and having a hard metal surface portion engaging said annular surface portion of said roller, said pressure ring being mounted in said housing only for movement in a direction substantially parallel to said axis; spring means operatively connected to said pressure ring for urging the same against said roller in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement with said pressure ring in a direction substantially parallel to said axis, said guiding means comprising a pair of ring members located concentrically about said axis and each being formed with a slot extending in a direction substantially parallel to said axis and being located about one of said shaft portions.

11. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces and an annular surface portion of hard metal located adjacent one of said side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; a pressure ring located about said axis and having a hard metal surface portion engaging said annular surface portion of said roller, said pressure ring being mounted in said housing only for movement in a direction substantially parallel to said axis; spring means operatively connected to said pressure ring for urging the same against said roller in a direction substantially parallel to said axis; and guiding means operatively connected to said shaft portions to guide said roller for free movement with said pressure ring in a directionsubstantially parallel to said axis, said guiding means comprising a pair of ring members located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions.

12. A grinding machine, comprising in combination, a housing; a grinding disc mounted in said housing, on a central shaft member for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof; at least one grinding roller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces and an annular surface portion of hard metal located adjacent one of said side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; a pressure ring located about said axis and having a hard metal surface portion engaging said annular surface portion of said roller, said pressure ring being mounted in said housing only for movement in a direction substantially parallel to said axis; spring means operatively connected to said pressure ring for urging the same against said roller in a direction substantially parallel to said axis; guiding means operatively connected to said shaft portions to guide said roller for free movement with said pressure ring in a direction substantially parallel to said axis, said guiding means comprising outer and inner ring members fixedly connected to each other, located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions; cap means mounted on said outer end of and being located about said central shaft member for rotation with respect thereto and being fixedly connected to said inner ring member to support the latter for rotation therewith; and fluid pressure means communicating with the interior of said cap means to prevent foreign matter from entering the same.

13. A grinding machine, comprising in combination, a housing; a grinding disc mount-ed in said housing, on a central shaft member for rotation about an axis, said grinding disc having an annular grinding face portion on one side thereof at least one grindingroller having a peripheral grinding face located against said grinding face portion of said disc and having opposite side faces and an annular surface portion of hard metal located adjacent one of said side faces; a pair of shaft portions respectively extending from said opposite side faces of said roller; a-pressure ring located about said axis and having a hard metal surface portion engaging said annular surface portion of said roller, said pressure ring being assess?) 11' mounted in said housing only for movement in a direction substantially parallel to said axis; spring means operatively connected to said pressure ring for urging the same against said roller in a direction substantially parallel to said axis; guiding means operatively portions to guide said roller for free movement with said pressure ring in a direction substantially parallel to said axis, said guiding means comprising outer and inner ring members fixedly connected to each other, located concentrically about said axis and each having a pair of plate members fixedly mounted thereon, extending in a direction substantially parallel to said central axis and respectively located on opposite sides of one of said shaft portions; cap means mounted on said outer end of and being located about said central'shaft member for rotation with respect thereto and being fixedly connected to said inner ring member to support the latter for rotation therewith; fluid pressure means communicating with the interior of said cap means to prevent foreign matter from entering the same; and bearing means located between said cap means and central shaft member to prevent tilting of said capmeans with respect to said shaft member.

14. A grinding machine comprising, in combination, a housing; a grinding disc turnably mounted in said housingfor rotation about a vertical-axis, and said grinding disc having a top face provided with an annular grinding surface; a plurality of grinding rollers located in spaced relation to each other over said grinding disc and each having a peripheral grinding face engaging said grinding surface of said grinding disc, said rollers each being mounted in said housing for rotation about an axis-inclined to said vertical axis and extending downwardly toward the same, and each of said rollers being formed adjacent said peripheral grinding face thereof with an annular, substantially V-shaped groove; an annular pressure ring located in said housing about said vertical axis and having an annular substantially V-shaped underside mating with and engaging said grooves of each roller on the side thereof distant from said grinding disc, said pressure ring being mounted in said housing for free movement in a vertical direction; and spring means engaging said pressure ring on the top side thereof and urging the same downwardly toward said grinding disc so that each of said rollers are turnable about said inclined axis while being yieldably movable in a vertical direction away from said. grinding disc.

15. A grinding machine comprising, in combination, a housing; a grinding disc turnably mou'ntedinsaid housing for rotation about a vertical axis, and said grinding disc having a top face provided with an annular grinding surface; a plurality of grinding rollers located in spaced relation to each other over said grinding disc and each having a peripheral grinding face engaging said grinding surface of said grinding disc, said rollers each being mounted in said housing for rotation about an axis inclined to said vertical axis and extending downwardly toward the same, and each of said rollers being formed adjacent said peripheral grinding face thereof with an annular, substantially V-shaped groove of a smaller diameter than said peripheral face thereof; an annular pressure ring located in said housing about said vertical axis and having an annular substantially V-shaped underside mating with and engaging said grooves of each roller on the side thereof distant from said grinding disc, said connected to said shaft pressure ring being-"mounted in Said housing: fo'f" freemoveinentin' a vertical direction; andspring means engaging saidp'ressu're ringon the top side thereof andui'ging the same downwardly toward said. grindingdisc so that each of'said' rollers are turnable about" said inclined axis while being" yieldably movable in a direction vertically. away" from said' grinding disc.

16.' A grinding machine comprising, in cornb'i nation, a housing; a grinding disc turnably mounted in said housing for rotationabo'uta ver tical axis, and said grinding disc havingia top face" provided with an annular grinding surface} a plurality of grinding rollers" located in" spaced relation'to each'other over's'aid'gi'inding disc and. each having a peripheralgr'inding face engaging said grinding surface of saidgrin'ding disc; said rollers each being mountedin saidhousing for rotation about an axisinclinjed to said vertical axis and extending downwardly towardthe same; an annular pressure ring'located'i'n said'housin'g about saidverti'cal' axis andhaving an" underside engaging each pressure roller onthe side thereof distantfromsaid grinding disc, said pressure ring, being mounted in said'housing for free'movernent' in averti'cal' direction; spring means engaging said'p'ressur'e'ring' on" the'top' side thereof and urging the same downwardly toward said'grinding disc so that each of said rollers are turn'able'. about said inclined axis while being yieldably movable in a' vertioal'direction awayfrom saidf grinding 'd'i'sc'; a 'pair'of shafts fixedto' 'eachofisaid' rollers and respectively extendingv from opposite sides thereofalong said'inclined axis; and an} nular guide means turnably mounted in said housing for rotation about saidverticalaxisand having portions located on opposite sideson each of said shafts to guide the latter for verti'cal'rnove menti- 1'71 A pulveri'zing mill comprising a circular pressurering; at least one wear-resistant running surface'on'saidpressure ring; springs'for exerting pressure" on; and resiliently controlling the verti cal movement of, said ring, 'a rotatably'mounte'd grinding track axially disposed with respect to saidpressure ring, means for'rotating, the grind ing track, a plurality of grinding roll's interposed between the pressure ring and the grindingt'ra'ck, at least one spacing element for maintaining'said grindingr'oll's in" fixedrela'tive' axial positions; and substantially" horizontal extensions on said grindin'gfrdlls for transmittingthesp'ring pressure from said'pre'ssure'ring, through the rolls to said'grinth ing track, said extensions being. of smaller diam eters than the rolls and" arranged axially were: trude from said grinding rolls and being'adapted to roll directly'agains't the' wearresist'ant surface of the pressure ring and'in' permanent clearance from the grinding track.

181A grinding machine comprising; in combination, support means; a grinding disc'turnably mounted onsaid support means for' 'r'ot'atio'n about a predetermined axis, said grinding discbeing provided with an annulargrindingsurface; a plurality of grindingrollers located in" spaced relation' to each other and each having" a peripheral grindingface engaging said grinding surface of saidg'rin'ding' di's'c, said rollerseachbeingnfounted for rotation about an axis .intersectingsaidpre determined axis and each of said rollers having adjacent'said peripheral grindingfacathereof an annular surface coaxial withsaid peripheral grinding facean'd' being ofa diiferent diameter than. said peripheral gr'in'din'g' face; and track riieans fion-rot'ata'bly mounted by support 13 means and frictionally engaging said annular surfaces of said grinding rollers, whereby during rotation of said grinding disc said grinding rollers turn in translation about said predetermined axis.

19. A grinding machine comprising, in combination, support means; a grinding disc turnably mounted on said support means for rotation about a predetermined axis, said grinding disc having an annular grinding surface; a plurality of grinding rollers located in spaced relation to each other and each having a peripheral grinding face engaging said grinding surface of said grinding disc, said rollers each being mounted for rotation about an axis inclined to said predetermined axis and extending toward said grinding disc, and each of said rollers being formed adjacent said peripheral grinding face thereof with an annular surface axial with said peripheral grinding face and being of a smaller diameter than the same; an annular pressure ring non-rotatably held by said support means and frictionally engaging said annular surfaces of said grinding rollers, whereby during rotation of said grinding disc said grinding rollers turn in translation about said predetermined axis.

20. A grinding machine comprising, in combination, support means; a grinding disc turnably mounted on said support means for rotation about a predetermined axis, said grinding disc having an annular grinding surface; an annular pressure ring non-rotatably held by said support means, being located about said axis, and being located opposite and facing said grinding disc; a plurality of grinding rollers located in spaced relation to each other between said grinding disc and pressure ring and each having a peripheral grinding face engaging said grinding surface of said grinding disc, said rollers each being mounted for rotation about an axis inclined to said predetermined axis and extending toward said grinding disc, and each of said rollers being formed outwardly of said peripheral grinding face thereof with an annular surface coaxial with said peripheral grinding face, being of a smaller diameter than the same, and frictionally engaging said annular pressure ring; and spring means engaging said pressure ring for urging the same toward said grinding disc, whereby during rotation of said grinding disc said grinding rollers turn in translation about said predetermined axis.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 324,664 Cummings Aug. 18, 1885 519,228 Bishop May 1, 1894 632,721 Johnson Sept. 12, 1899 810,830 Wegerif Jan. 23, 1906 822,913 Boss June 12, 1906 829,173 Sackett Aug. 21, 1906 835,104 Elpass Nov. 6,1906

1,264,532 Lane Apr. 30, 1918 1,401,716 McCrae Dec. 27, 1921 1,840,366 Loesche Jan. 12, 1932 2,394,048 Farfan Feb. 5, 1946 FOREIGN PATENTS Number Country Date 12,660 Germany Feb. 26, 1831 855,765 France Feb. 26, 1940 

